Physiology of the Proximal Tubule Flashcards
Where does the majority of reabsorption occur?
proximal tubule
What is the average GFR?
125 ml/min
What substances should be completley reabsorbed by the kidneys?
glucose
amino acids
What substances should be completely secreted by the kidneys?
creatinine
How many ml a min is absorbed by the proximal tubule?
80 ml/min
How many ml a min flows into the loop of henle?
45 ml/min
What is the osmotic concentration of the fluid reabsorbed in the proximal tubule?
300 - same as filtrate
What is transcellular reabsorption?
substance needs to go through the epithelial cell to be reabsorbed into the blood
What is paracellular reabsorption?
substance goes inbetween adjacent epithelial cells to be reabsorbed into the blood
Where are Na/K pumps found?
basolateral membrane
Where is the Na/H antiporter found?
apical membrane
What is oncotic drag?
the net movement of sodium transcellularly from filtrate to blood up an electrical gradient
this allows the net movement of Cl and H2O paracellularly into capillaries
and glucose is moved into the capillaries by facilitated diffusion
What is the purpose of oncotic drag?
salt and water gets into the capillaries
What does Tm stand for?
transport maximum
What doees Tm for glucose mean?
if the plasma glucose concentration increases massively then it will saturate the mechanisms that transport glucoose and therefore glucose will be peed out - diabetes
